We have synthesized a series of novel SERMs bearing a ferrocenyl unit based on a three-dimensional oxabicyclo[2.2.1]heptene core scaffold. These compounds displayed high receptor binding affinities as well as ERα or ERβ selectivity. In cell proliferation assays, we found that these ligands were cytotoxic at micromolar concentrations in both ER-positive and ER-negative breast cancer cells. On further examination, we found that the antiproliferative effects of compounds 9b, 10h and 11b on MCF-7 cells line does not arise from antiestrogenicity, but rather proceeds through a cytotoxic pathway. Possible mechanisms for the unique activities of these ligands were also investigated by molecular modeling. These new ligands could act as scaffolds for the development of novel anti-breast cancer agents.